A study using a xenograft breast carcinoma model has shown that an antibody engineered to prevent Fc binding to FcγRIIIa and specific to Her2/neu [Human Epidermal Growth Factor Receptor (EGFR) 2, CD340] which is overexpressed in certain aggressive types of breast cancer, was, in contrary to its murine parental antibody targeting Her2/neu, unable to arrest tumor growth in vivo (Clynes et al., 2000). The gene discussed is ERBB2; the disease is neoplasm.